There are no direct comparisons between biologic therapies for the treatment of JIA, they write, but "the maintained improvements in disease activity reported here with long-term abatacept treatment appear to be consistent with observations for etanercept, suggesting that abatacept is a clinically efficacious alternative option, which is also well tolerated and confers high patient retention."

Led by Daniel J. Lovell, MD, MPH, at Cincinnati Children's Hospital Medical Center, the investigators examined the safety, efficacy, and patient-reported outcomes obtained with abatacept in 153 JIA patients who entered an open-label, long-term extension of an international randomized, placebo-controlled phase III trial. During the open-label extension, patients received abatacept up to a dose of 10 mg/kg, to a maximum of 1,000 mg, and were followed for up to 7 years.

At entry into the LTE, disease duration was a mean of 4.1 years, and patients had an average of 16.0 joints with active disease and significant disability. Total exposure to abatacept across the entire study for patients treated in the LTE was 683.4 patient-years.

The overall incidence ratios (IRs) of adverse events and serious adverse events were 209.11 (95% CI 179.11-242.70) and 5.62 (95% CI 3.92-7.82) events/100 patient-years of exposure, respectively. The IRs of adverse events and serious adverse events during the LTE did not increase relative to the short-term treatment period.

The overall IR for infections during the cumulative period was 83.80 (95% CI 70.80-98.49). The most frequent infections reported were nasopharyngitis, upper respiratory tract infection, and influenza.

The IR for serious infections was 1.65 (95% CI 0.82-2.95) during cumulative abatacept treatment. The most frequently reported serious infections were pyelonephritis, bacterial arthritis, and appendicitis. The IRs of infections and serious infections during cumulative abatacept treatment did not increase relative to the short-term treatment period.

The overall IR for autoimmune events was 1.18 (95% CI 0.51-2.32). The IR of autoimmune events during the cumulative abatacept period decreased relative to the short-term treatment period, the authors note, "as seen in other LTE studies of biologics in JIA."

Two patients developed antibodies to the whole abatacept molecule and 39 exhibited an antibody response to the CTLA-4 region alone. Nine patients who developed an antibody response to the CTLA-4 region discontinued treatment during the LTE, three due to lack of efficacy, two who were lost to follow-up and four due to other reasons.

JIA ACR responses with abatacept during the initial 4-month lead-in phase of the study were maintained over time with continued treatment. In an intent-to-treat analysis, "the proportions of patients achieving a JIA ACR 90 response or clinically inactive disease status remained relatively stable during the LTE (21% to 27% or 16% to 22%, respectively)," the authors state. "JIA ACR 30 and 50 responses declined over time, which is likely reflective of patients discontinuing treatment."

An analysis of patient-reported outcomes showed progressive improvements in CHQ score throughout the study for patients who remained on treatment, with patients achieving mean scores that were comparable to those of healthy children. "Improvements in CHQ summary scores gained after initial short-term treatment were also maintained with continued long-term therapy and were generally within the range for healthy children," they write. "Patients in all treatment groups experienced reductions in pain and improvement in sleep quality that were maintained with continued treatment." Improvements in activity participation were also maintained with continued treatment.

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